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ISO-14644-1 vs. Fed 209E and other cleanrooms classification standards

floor to ceiling windows
Figure 1. ISO-7/Class 10k Cleanroom
ISO-14644-1 is the most well known and global cleanroom classification standard but only one of many. Other cleanroom classification standards include FED 209E, EU GMP Annex, British BS 5295, USP797/800. The FED Std 209E cleanroom classification was developed for the aerospace and electronics industry in the USA. The EU GMP cleanroom classification is for the European Community pharmaceutical and medical device industry. USP is for United States compounding pharmacies.
Class Maximum  Particles/m³ FED STD 209E equivalent
>0.1 um >0.2 um >0.3 um >0.5 um >1 um >5 um
ISO 1 10 2
ISO 2 100 24 10 4
ISO 3 1,000 237 102 35 8 Class 1
ISO 4 10,000 2,370 1,020 352 83 Class 10
ISO 5 100,000 23,700 10,200 3,520 832  29 Class 100
ISO 6 1,000,000 237,000 102,000 35,200 8,320 293 Class 1,000
ISO 7 352,000 83,200 2,930 Class 10,000
ISO 8 3,520,000 832,000 29,300 Class 100,000
ISO 9 35,200,000 8,320,000 293,000 Room Air
Table 1. ISO-14644-1 Cleanroom Classifications


ISO-14644-1 is the cleanroom classification defined by the International Organization for Standardization (ISO) headquartered in Geneva Switzerland. Units are particles per meters cubed. Pharmaceutical, Medical Device, and Food companies are required by FDA to comply with GMP (Good manufacturing Practices) and CGMP (Current Good Manufacturing Practices) by maintaining controlled environment including cleanrooms. ISO-14644-1 is the most often used cleanroom standard and is also used by non-FDA regulated bodies such as semiconductor industry, hospitals, aerospace industry, laser industry, auto industry and government laboratories.

Class Maximum  Particles/ft³ ISO equivalent
>0.1 um >0.2 um >0.3 um >0.5 um >5 um
 1 35 7 3 1 ISO3
 10 350 75 30 10 ISO4
100 100 ISO5
1000 1000 7 ISO6
10,000 10,000 70 ISO7
100,000 100,000 700 ISO8
Table 2. Federal Standard 209E Cleanroom Classifications

Fed Std 209E

Fed Std 209E was defined by United States Government in 1963. It was officially discontinued in 2001 but is still used in industry. There is a close correlation between ISO-14644-1 cleanroom classes and FED Std 209E cleanroom classes. The primary difference is ISO-14644-1 lists particles per meter cubed (m3) and Fed Std 209E lists particles per feet cubed (ft3).

Grade At Rest >0.5 um/M3 At Rest >5um/M3 Operational >0.5um/M3 Operational >5um/M3 Equivalent ISO at rest/operational Equivalent Fed209E at rest / operational
A 3,520 20 3,520 20 ISO-5/5 100/100
B 3,520 29 352,000 2,900 ISO-5/7 100/10k
C 352,000 2,900 3,520,000 29,000 ISO-7/8 10k/100k
D 3,520,000 29,000 not defined not defined ISO-8/na 100k/na
Table 3. EU GMP Annex Cleanroom Classifications

EU GMP Annex European Community

EU GMP - A, B, C and D. For sterile pharmaceutical and medical device manufacturing and CGMP. It has both at rest and operational particle requirement. Issued by European Union.

BS 5295 cleanroom classes
Table 4. British BS 5295 Cleanroom Classifications

BS 5295 British cleanroom standard was published in 1989. It was replaced in 2019 by British version of ISO-14644-1 cleanroom classification.

2x2 cleanroom pass thru
Figure 2. USP797 Cleanroom Pass Thru

USP797/800 Classification

USP 797/800 is a United States standard developed by the United States Pharmacopeial Convention (USP). It is for compounding pharmacies. USP 797 focus on protection of patients by regulating sterile drug compounding. USP800 focuses on protection of workers in the compounding pharmacies dealing with hazardous drugs. USP800 cleanrooms are required to be negative pressure. USP797/800 compounding pharmacies typically are ISO-7 with ISO-5 gloves boxes or hoods and ISO-8 anterooms. They often have interlocked pass thru’s to transfer finished prescriptions to outside of cleanroom.


There are multiple cleanroom classification systems. ISO-14644-1 is the most popular and is used globally across all industries including pharmaceutical and medical device manufacturing. Fed Std 209E was a US based cleanroom classification system developed primarily for aerospace and electronics industries. EU Annex European community is for GMP sterile pharmaceutical and medical device manufacturing for European Community. USP797/800 is cleanroom classification for US based compounding pharmacies.

The author Anthony Chien has worked at American Cleanroom Systems for past 12 years.  He has more than 40 years of cleanroom experience. Anthony has a BS and MS in Electrical Engineering specializing in semiconductor manufacturing from the University of Illinois. American Cleanroom Systems is a design build modular cleanroom manufacturer based in Rancho Santa Margarita CA. It is expert in ISO-5 thru ISO-8 (class 100 to class 100k) modular cleanrooms for pharmaceutical cleanrooms, medical device cleanrooms, and industrial cleanrooms.

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